Scanning tools exist that scan the data on a storage system for a variety of purposes including, anti-virus processing, keyword based file classification, security audits, and others. In many computer system environments, a file system, logical volume manager, database and/or other mapping layer provides an interface between the data units on a storage system and one or more clients that access the data, so that the data is accessed by clients in the form of logical storage objects (e.g., files, logical volumes, database records) rather than having the client directly access the data units in the storage system. Scanning tools typically examine the data stored on the storage system in logical objects presented to one or more clients. For example, in a computer system including a file system, a scanning tool may scan files in the file system and examine file system metadata associated with a file to determine the identity and location of the file's data units stored on the storage system.
Some computer systems may implement data reduction methods to reduce the amount of storage required to store data units. An example of a data reduction method is redundant data elimination (RDE), sometimes also known as data deduplication. RDE is a technique that allows a data unit (e.g., data block, etc.) shared by multiple storage objects to be stored fewer times on physical storage than the number of logical objects that share the data unit. Systems employing RDE typically accomplish this through the use of mapping tables that translate object contents into references to a shared data unit. Such data reduction methods are generally implemented in such a way as to be transparent to client systems, thereby preserving conventional storage system behavior.